Liquid polymer composition and use thereof

ABSTRACT

A liquid polymer composition contains: 
     (A) a liquid low molecular weight ethylene-α-olefin copolymer comprising 30 to 70 mol % of ethylene component units and 30 to 70 mol % of α-olefin component units, having a number average molecular weight (Mn) in the range of 150 to 10000, with a Q-value (weight average molecular weight/number average molecular weight) of 3 or less, and 
     (B) A high molecular weight polymer which is in an amount of 0.05 to 100 parts by weight based on 100 parts by weight of the liquid low molecular weight polymer (A), having a number average molecular weight (Mn) of 20000 or higher, witha Q-value of 6 or less, and is soluble in the liquid low molecular weight polymer (A), which liquid polymer composition has an excellent viscosity characteristic, lubrication characteristic, and oxidation stability, without denaturation by moisture adsorption, and therefore, is suitable for use as an actuation oil.

TECHNICAL FIELD

The present invention relates to a liquid polymer composition having anexcellent lubrication characteristic, viscosity characteristic, andoxidation stability over a wide temperature range of from a lowtemperature to a high temperature, and an actuation oil compositioncomprising the liquid polymer composition. The term "actuation oil" usedin this specification includes a brake fluid.

BACKGROUND ART

In the field of mechanical devices used, for example, in aircraft andautomobiles, many actuation oils are used as the pressure transmissionoils. Of these actuation oils, the actuation oils for use in aircraftand automobiles must have a low viscosity and small temperaturedependency, as well as an excellent lubrication characteristic andexcellent oxidation stability over a broad temperature range of from alow temperature to a high temperature.

In the prior art, as the actuation oil in the above fields, an extremelylow viscosity silicone oil or low viscosity mineral oil is utilized, andprimarily glycol ethers are used as brake fluids. However, although anextremely low viscosity silicone oil may have an excellent viscositycharacteristic, the compression ratio thereof is high and thelubrication characteristic is unsatisfactory. Also, a low viscositymineral oil does not have a satisfactory low temperature viscositycharacteristic or oxidation stability, and glycol ethers not only havean unsatisfactory low temperature viscosity, but also have a lowerboiling temperature caused by moisture absorption stemming from a highhygroscopic property. Accordingly, there is a strong demand for anactuation oil composition having an excellent viscosity characteristic,lubrication characteristic, and oxidation stability, and no denaturationcaused by moisture absorption.

In the prior art, several proposals have been made concerning asynthetic lubricant oil comprising a liquid low molecular weightpolymer. For example, Japanese Examined Patent Application (Kokoku) No.47-21650 proposes the use of a copolymer distillate of anethylene-propylene copolymer containing ethylene components at aspecific ratio obtained by polymerization from which the low boilingdistillate has been removed by non-destructive rectification orrectification after applying treatments such as cracking, hydrogenation,and dewaxing extraction. However, such a synthetic lubricant oilcomprising a copolymer distillate is not a lubricant having an excellentbalance of properties such as viscosity index, pour point, ignitionpoint, shear stability, oxidation stability, thermal stability, oil filmstrength and further, even if the copolymer distillate can be utilizedas an actuation oil, it cannot be utilized as an actuation oil having anexcellent viscosity characteristic, lubrication characteristic, andoxidation stability over a broad temperature range.

Also, the present Applicant has proposed, in Japanese Unexamined PatentApplication (Kokai) No. 57-117595, an ethylene-α-olefin copolymersynthetic lubricant oil containing 30 to 70 mol% of ethylene having anumber average molecular weight of 300 to 2000, and a statisticmolecular weight distribution with a Q-value (i.e., weight averagemolecular weight/number average molecular weight) of 3 or less. Theethylene-α-olefin copolymer according to this proposal has an excellentviscosity index, pour point, ignition point, shear stability, thermalstability, and oil film strength, and can exhibit an excellentperformance when used as a synthetic lubricant. However, when thiscopolymer is utilized as an actuation oil, it is still unsatisfactoryfrom the viewpoint of the viscosity characteristic over a broadtemperature range.

Furthermore, Japanese Unexamined Patent Publication (Kokai) No.48-65205, Japanese Unexamined Patent Publication (Kokai) No. 51-112809,and Japanese Examined Patent Publication (Kokoku) No. 47-42723 allpropose lubricant oil compositions in which specific low crystallineethylene-propylene copolymers are formulated as an viscosity indeximprover in lubricant oils. However, even if these lubricanting oils areutilized as actuation oils, they do not have a satisfactory viscositycharacteristic, lubrication characteristic and oxidation stability overa broad temperature range.

DISCLOSURE OF THE INVENTION

An object of the present invention, in view of the above-mentioned stateof the prior art concerning the actuation oil as a pressure transmissionmedium for mechanical devices in such as aircraft and automobiles is toprovide a liquid polymer composition having an excellent viscositycharacteristic, lubrication characteristic and oxidation stability overa broad temperature range of from a low temperature to a hightemperature and free from denaturation by moisture absorption.

In accordance with the present invention, there is provided a liquidpolymer composition comprising:

(A) a liquid low molecular weight ethylene-α-olefin copolymer comprising30 to 70 mol% of ethylene component units and 30 to 70 mol% of α-olefincomponent units, having a number average molecular weight (Mn) in therange of 150 to 10000, with a Q-value (weight average molecularweight/number average molecular weight) of 3 or less, and

(B) a high molecular weight polymer which is in an amount of 0.05 to 100parts by weight, based on 100 parts by weight of the liquid lowmolecular weight polymer (A), having a number average molecular weight(Mn) of 20000 or higher, with a Q-value of 6 or less, and is soluble inthe liquid low molecular weight polymer (A), as a first invention, andfurther an actuation oil composition comprising the liquid polymercomposition, as a second invention.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

The liquid low molecular weight ethylene-α-olefin copolymer (A) to beformulated in the liquid polymer composition of the present invention isa transparent liquid low molecular weight ethylene-α-olefin copolymercomprising 30 to 70 mol% of ethylene component units, preferably rangingfrom 40 to 60 mol%, having a number average molecular weight (Mn) asmeasured by gel permeation chromatography (GPC) in the range of 150 to10000, preferably 150 to 5000, particularly preferably 150 to 2000, mostpreferably 200 to 1000, with a Q-value (i.e., weight average molecularweight/number average molecular weight) as measured by GPC of 3 or less,preferably 2.8 or less, particularly preferably 2.5 or less. The liquidlow molecular weight ethylene-α-olefin copolymer within the abovephysical properties range has the advantage of an excellent oxidationstability and low temperature fluidity when formed into an actuation oilcomposition, by blending this copolymer with the high molecular weightpolymer (B).

Also, the standard deviation value σ of the ethylene composition of theabove liquid low molecular weight ethylene-α-olefin copolymer is withinthe range of generally from 0 to 3, preferably from 0 to 2, particularlypreferably from 0 to 1. The standard deviation value σ of the ethylenecomposition of the liquid low molecular weight ethylene-α-olefincopolymer was determined by a solvent extraction of the above-mentionedcopolymer using acetone/hexane solvent mixtures having different mixingrations, dividing the extract into five fractions with differentcompositions, determining the ethylene compositions of theethylene-α-olefin copolymers of the respective fractions according to IRanalysis, and calculating according to the following formula by usingthe ethylene compositions and the weight ratios of the respectivefractions. A larger standard deviation value σ indicates a broadercomposition distribution. ##EQU1##

Wherein, Ei represents the ethylene composition of the fraction i, Wirepresents the weight ratio of the fraction i, and E represents theaverage ethylene composition of the copolymer.

Examples of the α-olefin component unit which is the constituent of theabove liquid low molecular weight ethylene-α-olefin copolymer areα-olefins having 3 to 20 carbon atoms such as propylene, 1-butene,1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene,-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and thelike, and this unit may be a mixed component of two or more kinds ofthese α-olefins.

The high molecular weight polymer (B) to be formulated in the liquidpolymer composition of the present invention is a high molecular weightpolymer soluble in the liquid low molecular weight polymer (A) having anumber average molecular weight (Mn) of 20000 or higher, preferablyranging from 40000 to 250000, with a Q-value (i.e., weight averagemolecular weight/number average molecular weight) of 6 or less,preferably 5 or less. The high molecular weight polymer within the aboverange of physical properties has the advantage that a good lubricationcharacteristics and oxidation stability can be obtained and a uniformactuation oil composition can be obtained, when blended with thecopolymer (A) to form an actuation oil composition.

Speciffic examples of the high molecular weight polymer (B) are α-olefinpolymers, conjugated diene-aromatic vinyl monomer copolymers orhydrogenated products thereof, (meth)acrylate type polymers. As theα-olefin polymer, homopolymers or copolymers of ethylene, propylene,1-butene, isobutylene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene,etc., may be included. More specifical examples are polyethylene,polypropylene, poly-1-butene, polyisobutylene, ethylene-propylenecopolymer, ethylene-1-butene copolymer, ethylene-1-hexene copolymer,ethylene-1-decene copolymer, and ethylene-propylene-diene copolymer. Asthe conjugated diene-aromatic vinyl monomer copolymer or hydrogenatedproduct thereof, styrene-butadiene block copolymers and hydrogenatedproducts thereof and styrene-isoprenestyrene block copolymers andhydrogenated products thereof can be exemplified.

As the (meth)acrylate polymer, homopolymers or copolymers of acrylicacid esters and/or methacrylic acid esters having alkyl groups with 1 to28 carbon atoms can be exemplified. Further, after polymerization of theabove-mentioned (meth)acrylic acid esters, vinyl monomers such asstyrene, α,β-unsaturated carboxilic acids or esters thereof may be alsocopolymerized in an amount of 50 parts by weight at the maximum.

The proportion of the soluble high molecular weight polymer (B) to beformulated in the liquid polymer composition of the present inventionmay be 0.05 to 100 parts by weight, preferably 0.05 to 50 parts byweight, particularly preferably 0.05 to 15 parts by weight, mostpreferably 0.1 to 10 parts by weight, based on 100 parts by weight ofthe liquid low molecular weight polymer (A).

Also, in the liquid polymer composition of the present invention, inaddition to the liquid low molecular weight ethylene-α-olefin copolymer(A) and the soluble high molecular weight polymer (B), it is possible toformulate, if desired, a mineral oil (neutral oil), low molecular eightα-olefin polymer, silicone type synthetic lubricant oil, ester typesynthetic lubricant oil, oxidation stabilizer, extreme-pressure agent,anti-rust additive, defoaming agent, abrasion preventive, and the like.The proportion of these components may be conveniently formulated asdesired within a range which does not impair the effect of the liquidpolymer composition of the present invention.

The composition of the present invention can be used for actuation oils(e.g., actuation oils for automobiles, aircraft), gear oils forautomobiles, gear oils for industrial use, metal working oils, engineoils, lubricant oils, and the like.

EXAMPLES

In the following, the present invention will now be explained in detailby referring to Examples, but these Examples do not in any way limit thepresent invention. The EP-1 to EP-8 and EH-1 used in the followingExamples were synthesized according to the method as described inJapanese Unexamined Patent Publication (Kokai) No. 57-123205 proposed bythe present Applicant.

EXAMPLE 1 (Starting Polymers)

(A) Low Molecular Weight Copolymer, EP-1 Mn 380, ethylene 53 mol%,propylene 47 mol%, Q-value 1.2, σ 0.1

(B) High Molecular Weight Polymer EP-2 Mn 50000, ethylene 60 mol%,propylene 40 mol%, Q-value 2.6

(Preparation of Composition)

The temperature of EP-1 was elevated to 100° C., and EP-2 was dissolvedtherein under stirring. The mixing ratio was 1.5 parts by weight, basedon 100 parts by weight of EP-1.

Measurements of the solution as shown in Table 1 were conducted. Theresults are shown in Table 3.

                  TABLE 1                                                         ______________________________________                                        Measurement Items                                                                          Unit     Measurement Conditions                                  ______________________________________                                        Viscosity    cSt      54.4 (°C.) JIS K 2283                                         cPs      -40 (°C.) following JIS D                                              2983                                                    Viscosity index       JIS K 2283                                              Load-Bearing                                                                  Capability   kg/cm.sup.2                                                                            Sota four-ball test (200 rpm)                                                 following JIS k 2519                                    Shear Stability                                                                            %        Sonication shear test                                                         following ASTM 2603                                                           (10 kHz, 100 W - 30 min.)                               ______________________________________                                    

EXAMPLE 2 (Starting Polymers)

(A) Low Molecular Weight Copolymer, EP1: as described in Example 1.

(B) High Molecular Weight Polymer, PMA-1

Into a glass reactor having a 2-liter volume and equipped with astirrer, a thermometer, a cooling pipe, and a nitrogen introducinginlet, were charged 500 g of a methacrylate with the composition shownin Table 2, 50 g of the above EP-1, and 4 g ofazobiscyclo-hexanecarbonitrile and, after the reaction was internallyreplaced with nitrogen gas, polymerization was carried out with stirringat 110°0 C. for 10 hours. Further, 450 g of the above EP-1 was addedunder stirring. This solution is called PMA-1. As a result of ananalysis of the polymer by gel permeation chromatography (GPC-1 Model A,produced by Shimazu Seisakusho), the number average molecular weight wasfound to be 50500, and the molecular weight distribution was 2.4.

                  TABLE 2                                                         ______________________________________                                                          Parts by weight                                             ______________________________________                                        Number of Carbon Atoms                                                                           4    30                                                    in Alkyl Group                                                                Number of Carbon Atoms                                                                          12    20                                                    in Alkyl Group                                                                Number of Carbon Atoms                                                                          14    25                                                    in Alkyl Group                                                                Number of Carbon Atoms                                                                          16    15                                                    in Alkyl Group                                                                Number of Carbon Atoms                                                                          18    10                                                    in Alkyl Group                                                                ______________________________________                                    

Next, the temperature of EP-1 was elevated to 100° C. and PMA-1 wasmixed therewith while stirring. The mixing ratio was 10 parts by weightof PMA-1 based on 100 parts by weight of EP-1. The same measurements ofthis solution as in Example 1 were carried out. The results are shown inTable 3.

EXAMPLE 3 (Starting Polymers)

(A) Low Molecular Weight Copolymer, EH-1 Mn 430, ethylene 50 mol%,1-hexene 50 mol%, Q-value 1.3, σ 0.2

(B) High Molecular Weight Polymer, PMA-1: as used in Example 2.

(Preparation of Composition)

In Example 2, EHR-1 was used instead of EP-1, but otherwise the sameprocedure as in Example 3 was carried out. The results are shown inTable 3.

EXAMPLE 4 (Starting Polymers)

(A) Low Molecular Weight Polymer, EP-3 Mn 410, ethylene 44 mol%,propylene 56 mol%, Q-value 1.2, σ 0.1

(B) High Molecular Weight Polymer, PMA-2

A polymerization of 65% by weight of methacrylate comprising 10% byweight of methacrylate with an alkyl group having 14 carbon atoms, 60%by weight of methacrylate of 16 carbon atoms, and 30% by weight ofmethacrylate of 18 carbon atoms was carried out with EP-1 as thesolvent. This EP-1 solution is called PMA-2. The polymer had an Mn of60000 and a molecular weight distribution of 2.2.

(Preparation of Composition)

Next, EP-3 and PMA-2 were mixed while stirring. The mixing proportionwas 10 parts by weight of PMA-2 based on 100 parts by weight of EP-3.The same measurements of this solution were carried out as in Example 1.The results are shown in Table 3.

EXAMPLE 5 (Starting Polymers)

(A) Low Molecular Weight Copolymer, EP-4 Mn 670, ethylene 49 mol%,propylene 51 mol%, Q-value 1.3, σ 0.1

(B) High Molecular Weight Polymer, PMA-1 as used in Example 2.

(Preparation of Composition)

In Example 2, EP-4 was used instead of EP-1, but otherwise the sameprocedure as in Example 2 was carried out. The results are shown inTable 3.

EXAMPLE 6

For the actuation oil composition in Example 2, the performances thereofas an actuation oil were examined according to the MIL-H-5606 (HYDRAULICFLUID, PETROLEUM BASE; AIRCRAFT, MISSILE, AND ORDNANCE) standard (thetest method shown in Table 4). The results are shown in Table 5.

EXAMPLE 7

The actuation composition was prepared in the same manner as in Example2 except that EP-9 (Mn 250, ethylene composition 49 mol%, propylenecomposition 51 mol%, Q-value 1.1, σ=0.1) was used instead of EP-1, andchanging the amount of PMA-1 mixed to 6.5 parts by weight based on 100parts by weight of EP-9, and the performances as an actuation oil wereexamined according to the MIL-H-81019D (HYDRAULIC FLUID, PETROLEUM BASE,ULTRA-LOW TEMPERATURE, METRIC) standard.

EXAMPLE 8

The performance of the composition of Example 5 as the brake fluid wereexamined according to ISO 7309-1985(E) (Road vehicles-Hydraulic brakingsystems-ISO reference petroleum base fluid) standard. The results areshown in Table 7.

COMPARATIVE EXAMPLE 1 (Starting Polymers)

(A) Low Molecular Weight Copolymer, EP-5 Mn 120, ethylene 50 mol%,propylene 50 mol%, Q-value 1.1, σ 0.1

(B) High Molecular Weight Polymer, PMA-1 as used in Example 2.

(Preparation of Composition)

As in Example 2, EP-5 and PMA-1 were mixed while stirring. The mixingproportion was 10 parts by weight of PMA-1 based on 100 parts by weightof EP-5. The same measurements of this fluid as in Example 1 werecarried out. The results are shown in Table 3.

COMPARATIVE EXAMPLE 2 (Starting Polymers)

(A) Low Molecular Weight Copolymer, EP-6 Mn 3200, ethylene 52 mol%,propylene 48 mol%, Q-value 2.4, σ 0.2

(B) High Molecular Weight Polymer, PMA-1 as used in Example 2

(Preparation of Composition)

As in Example 1, the temperature of EP-6 was elevated to 100° C. andmixed while stirring with PMA-1. The mixing proportion was 10 parts byweight of PMA-1 based on 100 parts by weight of EP-6. The samemeasurements of this fluid as in Example 1 were carried out. The resultsare shown in Table 3.

COMPARATIVE EXAMPLE 3 (Starting Polymers)

(A) Low Molecular Weight copolymer, EP-7 Mn 810, ethylene 10 mol%,propylene 90 mol%, Q-value 1.6, α 0.2

(B) High Molecular Weight Polymer, PMA-1 as used in Example 2

(Preparation of Composition)

Comparative Example 2 was repeated except that EP-7 was used instead ofthe EP-6 used in Comparative Example 2. The results are shown in Table3.

COMPARATIVE EXAMPLE 4 (Starting Polymers)

(A) Low Molecular Weight Copolymer, EP-8 Mn 400, ethylene 81 mol%,propylene 19 mol%, Q-value 1.4, σ 0.3

(B) High Molecular Weight Polymer, PMA-1 as used in Example 2

(Preparation of Composition)

Comparative Example 2 was repeated except that EP-8 was used instead ofthe EP-6 used in Comparative Example 2. The results are shown in Table3.

COMPARATIVE EXAMPLE 5

The actuation oil characteristics of a commercially available siliconeoil (SH-200, produced by Toray Silicone Co.), were measured. The resultsare shown in Table 3.

COMPARATIVE EXAMPLE 6

The actuation oil characteristics of a commercially available mineraloil (Hydrofluric Oil SV produced by Fuji Kosan Co.), were measured. Theresults are shown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________    Quality performance                                                                       Example             Comparative Example                           items       1   2   3   4   5   1   2  3   4  5   6                           __________________________________________________________________________    Viscosity cSt 54.4° C.                                                               12.5                                                                            10.2                                                                              10.5                                                                              11.0                                                                              25  3.0 >10.sup.4                                                                        2000                                                                              >10.sup.6                                                                         15  25                         Viscosity cPs -40° C.                                                              1000                                                                              400 600 800 1000                                                                              30  >10.sup.6                                                                        >10.sup.6                                                                         -- 150 >10.sup.5                   Viscosity index                                                                           230 465 415 390 300 750 400                                                                              200 -- 500 120                         Load bearing                                                                                3.5                                                                             3.5 4.0 4.0   5.0                                                                             2.0 --    4.5                                                                            --    1.5                                                                               4.0                      ability kg/cm.sup.2                                                           (four-ball test 200 rpm)                                                      Shear stability                                                               Viscosity lowering                                                                        15  21  24  20  15  25  --  20 --  0   0                          (10 kHz 100 W-30 min.)                                                        __________________________________________________________________________

                  TABLE 4                                                         ______________________________________                                        Test methods                                                                  Test items            ASTM No.                                                ______________________________________                                        Viscosity             D445                                                    Pour Point            D97                                                     Ignition point        D93                                                     Acid value            D664                                                    Weight reduction      D972 (note 1)                                           by heating vaporization                                                       Water content         D1744                                                   ______________________________________                                         (note 1)                                                                      conducted under the conditions of 71° C., 6 hr                    

                  TABLE 5                                                         ______________________________________                                        Results of Example 2 actuation                                                oil for MIL-H-5606E                                                           Property items  Standard     Results                                          ______________________________________                                        Viscosity (cSt 100° C.)                                                                4.90 or more 5.71 cSt                                         Viscosity (cSt 40° C.)                                                                 13.2 or more 13.3 cSt                                         Viscosity (cSt -40° C.)                                                                600 or less  400 cSt                                          Viscosity (cSt -54° C.)                                                                2500 or less 1800 cSt                                         Pour point      -60° C. or less                                                                     -65° C. or less                           Ignition point  82° C. or less                                                                      120                                              Acid value      0.20 or less 0.01 or less                                     Note (1)                                                                      Weight reduction                                                                              20 or less    8                                               by heating vaporization (%)                                                   Water content (ppm)                                                                           100 or less  30                                               ______________________________________                                         Note (1)                                                                      reduction after 71° C. × 6 hr                                    (Sample weight before heatingSample weight after heating)/Sample weight       before heating                                                           

                  TABLE 6                                                         ______________________________________                                        Results of Example 7 actuation                                                oil for MIL-H-81019D                                                          Property items  Standard      Results                                         ______________________________________                                        Viscosity (m.sup.2 /s)                                                        100° C.  2.5 × 10.sup.-6 or more                                                               2.6 × 10.sup.-6                           -54° C.  800 × 10.sup.-6 or less                                                               190 × 10.sup.-6                           -70° C.  0.008 or less 0.0012                                          Pour point (°C.)                                                                       -75 or less   -78 or less                                     Ignition point (°C.)                                                                   95 or more    120                                             Combustion point (°C.)                                                                 110 or more   138                                             Neutralization value                                                                          0.2 or less   0.01 or less                                    Weight reduction                                                                              12 or less    9                                               by heating vaporization                                                       (wt %. 70° C. ± 1° C. 6 hr)                                  Water content (ppm)                                                                           200           30                                              ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Results of Example 5 composition for ISO-7309                                                                         Commer-                                                                       cially                                                                        available                                                                     mineral                               Proper-          Test            Example                                                                              oil type                              ties    Unit     method   Value  5      brake oil                             ______________________________________                                        Dynamic mm.sup.2 /s                                                                            ISO 3104 >6     10.5   6.65                                  viscosity                                                                     (100° C.)                                                              Dynamic mm.sup.2 /s                                                                            ISO 3104 <2000  1000   1800                                  viscosity                                                                     (-40° C.)                                                              Pour point                                                                            °C.                                                                             ISO 3016 <-50   -55    --                                    Ignition                                                                              °C.                                                                             ISP 2592 >105   240    105                                   point                                                                         Initial °C.                                                                             ISO 3405 >240   285    245                                   distilling                                                                    point                                                                         Neutrali-                                                                             mg       ISO 6618 <0.2   0.01 or                                                                              --                                    zation value                                                                          KOH/g                    less                                         Phosphorus                                                                            ppm      Fluore-  800 ± 80                                                                          not    --                                                     scent           detected                                                      X-ray                                                                         (XFR)                                                        ______________________________________                                    

EXAMPLE 9 (Starting Polymers)

(A) Low Molecular Weight Copolymer EP-10 Mn 3810, ethylene 54 mol%,propylene 46 mol%, Q-value 1.2, σ 0.1

(B) High Molecular Weight Polymer, PMA-1 as used in Example 2

(C) Low Molecular Weight α-Olefin Polymer PAO-1 GULF OIL CHEMICALSCOMPANY/GULF SYNFLUID® BASE FLUID 4cSt

(Preparation of Composition)

In Example 2, a mixture of EP-10/PAO-1=50/50 (wt/wt) was used instead ofEP-1 and 0.3 parts of PMA-1 were used, based on 100 parts by weight ofthe EP-10/PAO-1 mixture, but otherwise the same procedure was followed.

The physical properties of the composition were a dynamic viscosity of98.0 cSt at 100° C., a dynamic viscosity of 880 cSt at 40° C., aviscosity index of 205, and a pour point of -40° C.

COMPARATIVE EXAMPLE 7

When the physical properties of a commercially available gear oilcomposition for industrial use (Bonknock SP3800, produced by NipponPetroleum K.K.) were measured, the respective properties were found tobe a dynamic viscosity of 99.5 cSt at 100° C., and 3620 cSt at 40° C., aviscosity index of 87, and a pour point of +2.5° C.

We claim:
 1. A liquid polymer composition comprising:(A) a liquid lowmolecular weight ethylene-α-olefin copolymer comprising 30 to 70 mol% ofethylene component units and 30 to 70 mol% of α-olefin component units,having a number average molecular weight (Mn) in the range of 150 to5,000, with a Q-value (i.e., weight average molecular weight/numberaverage molecular weight) of 3 or less, and (B) a high molecular weightpolymer which is in an amount of 0.05 to 100 parts by weight based on100 parts by weight of the liquid low molecular weight polymer (A),having a number average molecular weight (Mn) of 20000 or higher, with aQ-value of 6 or less, and is soluble in the liquid low molecular weightpolymer (A).
 2. A composition as claimed in claim 1, wherein the contentof ethylene component in the liquid low molecular weightethylene-α-olefin copolymer is 40 to 60 mol%, and the number averagemolecular weight of the copolymer is 150 to 2000, and Q-value is 2.8 orless.
 3. A composition as claimed in claim 1, wherein the α-olefin has 3to 20 carbon atoms.
 4. A composition as claimed in claim 1, wherein thehigh molecular weight polymer (B) is an α-olefin polymer, a conjugateddiene-aromatic vinyl monomer copolymer or hydrogenated product thereofor (meth)acrylate copolymer.
 5. A composition as claimed in claim 1,wherein the proportion of the high molecular weight polymer (B) is 0.05to 15 parts by weight, based on 100 parts by weight of the liquidpolymer (A).
 6. An actuation oil comprising a liquid polymer compositioncomprising:(A) a liquid low molecular weight ethylene-α-olefin copolymercomprising 30 to 70 mol% of ethylene component units and 30 to 70 mol%of α-olefin component units, having a number average molecular weight(Mn) in the range of 150 to 5,000, with a Q-value (weight averagemolecular weight/number average molecular weight) of 3 or less, and (B)a high molecular weight polymer which is in an amount of 0.05 to 100parts by weight, based on 100 parts by weight of the liquid lowmolecular weight polymer (A), having a number average molecular weight(Mn) of 20000 or higher, with a Q-value of 6 or less, and is soluble inthe liquid low molecular weight polymer (A).
 7. An actuation oil asclaimed in claim 6, wherein the content of ethylene component in theliquid low molecular weight ethylene-α-olefin copolymer is 40 to 60mol%, and the number average molecular weight of the copolymer is 150 to2000, and Q-value is 2.8 or less.
 8. An actuation oil as claimed inclaim 6, wherein the α-olefin has 3 to 20 carbon atoms.
 9. An actuationoil as claimed in claim 6, wherein the high molecular weight polymer (B)is an α-olefin polymer, a conjugated diene-aromatic vinyl monomercopolymer or hydrogenated product thereof or (meth)acrylate copolymer.10. An actuation oil as claimed in claim 6, wherein the proportion ofthe high molecular weight polymer (B) is 0.05 to 15 parts by weight,based on 100 parts by weight of the liquid polymer (A).
 11. Acomposition as claimed in claim 1, wherein the proportion of the highmolecular weight polymer (B) is 0.05 to 15 parts by weight, based on 100parts by weight of the liquid polymer (A).
 12. An actuation oil asclaimed in claim 6, wherein the proportion of the high molecular weightpolymer (B) is 0.05 to 15 parts by weight, based on 100 parts by weightof the liquid polymer (A).